There has been a plurality of variations of adjustable width headers for use with harvesters and some of these headers, with adjustable row units, have been in existence for approximately 25 years. The original corn head for use with a harvester was with fixed spacing between the row units and this design was embodied in U.S. Reissued Pat. No. 27,554, which was originally issued in 1966. Subsequently, it was determined that a header in which the width between the row units could be varied to match the various widths of corn rows was desirable. Several embodiments of this variable row width header were and are still marketed. These headers are described in U.S. Pat. No. 3,520,121 patented Jul. 14, 1970, one of the early headers which permitted the modification of row widths in the field. Another narrow row header is disclosed in U.S. Pat. No. 5,704,202, which is incorporated by reference herein in its entirety.
During the past 25 to 30 years since the introduction of the variable row-width planters and headers, much research and development has occurred in the agronomics of the growing of corn. This research has concentrated on reaching the maximum population by varying row widths and spacing between plants. The original corn head and row units were and are capable of harvesting row widths between 28 and 40 inches.
Recently, 12-15 inch rows of corn with varied spacing have been studied for yields and other agronomic affects. Such narrow row widths provide improved erosion control, higher population, higher yield, and better weed control. The narrow rows require less chemical use and in some cases utilize only one-half of much weed control. All of these factors benefit the environment.